Carbon fiber composition including graphene nano-powder and fabrication method for carbon fiber using the same

ABSTRACT

The present disclosure relates to a carbon fiber composition and a fabrication method for high-performance carbon fiber using the same. The method can fabricate high-performance carbon fiber (or graphite fiber) with lowering a graphitization temperature by using graphene carbon fiber composition including nano-sized graphene.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119(a) of KoreanPatent Application No. 10-2012-0076759, filed on Jul. 13, 2012, in theKorean Intellectual Property Office. The entire disclosures of theearlier filed applications are incorporated herein by reference for allpurposes.

BACKGROUND OF THE DISCLOSURE

1. Field of the Disclosure

The following description relates to a carbon fiber composition and afabrication method for carbon fiber. The carbon fiber compositionincludes nano-sized graphene, and the fabrication method for carbonfiber also uses the same composition. Through the method, agraphitization temperature for fabrication of high-performance carbonfiber (or graphite fiber) can be lowered.

2. Background of the Disclosure

Carbon fiber is a fiber-type carbon material having a diameter of 10 μmor less, which can be categorized according to a starting material (orcomposition) and a fabrication method into polyacrylonitrile (PAN)-basedcarbon fiber, pitch-based carbon fiber, rayon-based carbon fiber,chemical vapor deposition (CVD)-based carbon fiber, etc.

The rayon-based carbon fiber was industrialized in 1963, and has beenused as reinforcing fiber of a composite material in the various field,such as aerospace, etc. However, with the advent of PAN or pitch-basedcarbon fiber which can be manufactured at relatively-cheaper price, theproduction amount of the rayon-based carbon fiber has drasticallydecreased since 1978, and recently the production of the rayon-basedcarbon fiber has been actually stopped. Further, since the CVD-basedcarbon fiber has a problem of a low product yield, the PAN-based carbonfiber and the pitch-based carbon fiber are being mainly utilized in thecarbon fiber-related industry.

Researches for enhancement of elastic modulus (elasticity) and strengthof carbon fiber and for development of preparing method with lowercosts, especially research on development of a new composition, isongoing. As a method for enhancing physical property of carbon fiber,research on decrease of a diameter into sub micron (several hundred ofnm) is also ongoing.

To prepare a high performance carbon fiber derived from PAN-based iscarbon fiber or pitch-based carbon fiber, a graphitization processshould be performed at a very high temperature of about 2,500° C. orgreater during the preparation process. Also, some kind of carbon fibermay be fabricated through a carbonization process at a temperature ofabout 800° C.˜1,500° C. only. However, in this case, the fabricatedcarbon fiber has lower performance than the high performance carbonfiber as mentioned above.

Since high-performance carbon fiber undergoes a graphitization process,it can be mentioned so-called “material of graphite structure”.Practically, it is reported that carbon fiber is composed of graphiteribbon (sheet-like, bent shaped, or loop shaped ones) [I. Mochida etal., Microstructure of mesophase pitch-based carbon fiber and itscontrol, Carbon 34 (1996) 941-956 (FIG. 4); Chan Kim, Fabrications andMicrostructural Characterizations of Multi-phase Carbon Nanofibers, J.of Future Fusion Technology 1 (2009) 19-25 (FIG. 9)]. The sheet-likegraphite has a thickness of about 5˜10 nm and a width of several μm, andthe carbon fiber has a diameter of 10 μm or less.

Recently, graphene has attracted much attention. Graphene is atwo-dimensional carbon material consisting of carbon atom with singlelayer having a thickness of about 0.4 nm. Since graphene is a basic unitof graphite (i.e., graphite is a stacked body with a plurality ofgraphene, it can be fabricated in the form of powder by decomposinggraphite. Graphene powder can be defined as an accumulation ofthree-dimensionally random graphene layers.

Considering that a particle size of graphite is several μm, it may beunderstood that graphene powder obtained by decomposing the graphitehave an average size of several nm˜several μm. However, an actual sizeof the graphene powder is a nano scale (1˜100 nm).

Recently, the inventors of this disclosure have proposed a method forfabricating graphene powder by mechanical decomposing helical AA′graphite (graphene helix stacked body) (Korean Registration Patent No.10-1040967). Here, the graphene has a width of 5 nm or less than, alength of 20 nm or less than, and a thickness of carbon atoms to puregraphene of 0.4 nm.

Generally, carbon fiber and graphite fiber are considered to be the samemeaning. However, carbon fiber and graphite fiber indicate fiber havingundergone a heating process at 800° C.˜1,500° C. and fiber havingundergone a graphitization process at 2,500° C. or more, respectively.Among carbon fibers used in the industry, high-performance carbon fiberof an excellent physical property (tensile modulus of about 350 GPa ormore) means fiber having undergone a graphitization process at 2,500° C.or more. Through the conventional method of fabrication carbon fiber, itis impossible to lower a graphitization temperature for fabricating suchhigh-performance carbon fiber, including PAN-based carbon fiber andpitch-based carbon fiber.

In the conventional art, there has been reports on technique of graphenecomposite nano (carbon) fiber. Here the graphene material is thingraphite having a thickness of about ˜10 nm, rather than graphene(referred to as ‘single-layered graphene’ or ‘multi-layered graphene’)[Sung-Yeon Jang et al., Graphene composite nanofiber and the preparationmethod thereof, Publication No. 10-2010-0099586].

SUMMARY OF THE DISCLOSURE

Therefore, an aspect of the detailed description is to provide agraphene carbon fiber composition capable of fabricatinghigh-performance carbon fiber with lowering a graphitizationtemperature.

Another aspect of the detailed description is to provide a method forfabricating high-performance graphene carbon fiber, capable ofperforming an excellent graphitization process at a temperature lowerthan the conventional one, using the graphene carbon fiber composition.

To achieve these and other advantages and in accordance with the purposeof this specification, as embodied and broadly described herein, thereis provided a graphene carbon fiber composition, comprising: acomposition for fabricating carbon fiber; and graphene powder, whereinthe graphene powder serves as a seed of graphite to be formed duringcarbon fiber fabricating processes.

The composition for fabricating carbon fiber includes one selected fromthe group consisting of polyacrylonitrile (PAN)-based carbon fiber,pitch-based carbon fiber, rayon-based carbon fiber and combinationsthereof.

To achieve these and other advantages and in accordance with the purposeof this specification, as embodied and broadly described herein, thereis also provided a method for fabricating high-performance carbon fiber,the method comprising steps of: a mixing step to fabricate a graphenesuspension by mixing a composition for fabricating carbon fiber withgraphene powder to form a graphene carbon fiber composition, anddispersing the graphene carbon fiber composition in a solvent, whereinthe composition for fabricating carbon fiber includes one selected fromthe group consisting of polyacrylonitrile (PAN)-based carbon fiber,pitch-based carbon fiber, rayon-based carbon fiber and combinationsthereof; a fabrication step to fabricate fibers by controlling aviscosity of the graphene suspension and performing a fiberizationprocess of the graphene suspension; a stabilization step to stabilizethe fibers; and a heat treatment step of fabricating nano ribbon-shapedgraphite by graphitization the stabilized the fibers at a temperatureless than 2,500° C.

The graphene powder included in the graphene carbon fiber compositionserves as a seed of graphite to be formed during high-performance carbonfiber fabricating processes.

In the present invention, high-performance carbon fiber indicates carbonfiber having an excellent physical property (tensile modulus of about350 GPa or more than), and may be fabricated by undergone agraphitization process at a temperature of 2,500° C. or more. Thehigh-performance carbon fiber is differentiated from general carbonfiber which can be obtained through a heating process at 800° C.˜1,500°C. The high-performance carbon fiber may be referred to as ‘graphitefiber’, but will be referred to as high-performance carbon fiber in thepresent invention.

Hereinafter, the present invention will be explained in more detail.

The graphene carbon fiber composite comprises a composition forfabricating carbon fiber and graphene powder.

The composition for fabricating carbon fiber includes one selected fromthe group consisting of PAN-based carbon fiber, pitch-based carbonfiber, rayon-based carbon fiber and a combination thereof.

In order to fabricate high-performance carbon fiber using thecomposition, a graphitization process should be performed at a hightemperature of 2,500° C. or more, which may require a high cost.

However, since the graphene carbon fiber composition comprises graphenepowder, a graphitization process can be performed at a temperature of2,500° C. or less. Further, high-performance carbon fiber can befabricated through a graphitization process at a temperature of about2,000° C.

The pitch may be anisotropic or isotropic pitch. In a case where thecomposition for fabricating carbon fiber includes anisotropic pitch, afabrication temperature may be relatively high, because the anisotropicpitch has a high molecular amount and a high softening temperature.

The graphene powder has a thickness of about 0.4 nm, and its lateraldimensions are 3˜100 nm (generally 5˜20 nm). The graphene powder may beagglomerated due to Van der Waals force. However, generally, thegraphene powder may seem to have a structure that graphene sheets arestacked in parallel to one another.

The graphene carbon fiber composition may be dispersed in a solvent. Thedispersion may be performed using ultrasonication treatment, etc. As thesolvent, it may be used any solvent capable of properly dispersing thegraphene carbon fiber composition. More specifically, the solvent may beone selected from the group consisting of alcohol, acetone,dimethylformamide (DMF), tetrahydrofuran (THF) and combinations thereof.The graphene carbon fiber composition may further comprise a viscositycontrol agent, a solvent, a solidification liquid, etc.

Based on 100 wt % of the sum of the composition for fabricating carbonfiber and the graphene powder, the weight of the graphene powder may bemore than 0.1 wt %, or may be in the range of more than 0.1 wt % and 50wt % or less. If the weight of the graphene powder is more than 0.1 wt %based on 100 wt % of the sum of the composition for fabricating carbonfiber and the graphene powder, a graphitization temperature forfabricating high-performance carbon fiber can be performed at atemperature lower than 2,500° C.

Based on 100 wt % of the sum of the composition for fabricating carbonfiber and the graphene powder, the weight of the graphene powder may be0.5 wt % or more, or may be 0.5˜50 wt %. If the weight of the graphenepowder is 0.5 wt % or more than, based on 100 wt % of the sum of thecomposition for fabricating carbon fiber and the graphene powder, agraphitization temperature for fabricating high-temperature carbon fibermay be performed at a temperature lower than 2,500° C., at a temperatureof at least 1,500° C.˜2,500° C., or at a temperature of 1,500° C.˜2,000°C.

The graphene carbon fiber composition may lower a graphitizationtemperature for fabricating high-performance carbon fiber, by comprisingnano-sized graphene powder. It is believed that this results from thatthe graphene powder serves as a seed of nano ribbon-shaped graphite tobe formed during a graphitization process. Considering that the formednano ribbon-shaped graphite has a size (length) of several tens of nm,it may be advantageous that the graphene powder serving as a seed has asize less than 10 nm.

A fabrication method for high-performance carbon fiber according toanother embodiment of this disclosure, comprises steps of a mixing stepand a heat treatment step.

The mixing step includes a step of fabricating a graphene suspension bymixing a composition for fabricating carbon fiber with graphene powderto form a graphene carbon fiber composition, and dispersing the graphenecarbon fiber composition in a solvent. The composition for fabricatingcarbon fiber included one selected from the group consisting ofpolyacrylonitrile (PAN)-based carbon fiber, pitch-based carbon fiber,rayon-based carbon fiber and combinations thereof.

The configuration and characteristics of the composition for fabricatingcarbon fiber and the graphene powder is the same as was explained in theabove, it is therefore omitted herein.

The graphene powder may be fabricated by decomposing a crystallinegraphite structure (commonly in a mechanical route). The crystallinegraphite structure may have grown in a helix shape. With the mechanicalroute, mass production of graphene powder is possible.

The graphene suspension may be fabricated by dispersing the graphenecarbon fiber composition in a solvent in a dispersed state. The solventwas aforementioned with the graphene carbon fiber composition accordingto the above, and thus its detailed explanations will be omitted inhere. The graphene suspension may be dispersed using ultrasonication,etc. within the mixing step.

The prepared graphene suspension may be fabricated as carbon fiberthrough a fiberization step, a stabilization step and a graphitizationstep (a heat treatment step).

The fiberization step may be performed after controlling a viscosity ofthe graphene suspension. Graphene carbon fiber may be fabricated in theform of continuous fiber, staple fiber, fabrics, etc., according to ausage purpose.

The stabilization step may be performed by maintaining the fiberfabricated during the fiberization step, in an oven for about 3 hours,under an oxidation atmosphere kept at about 200° C.˜400° C.

The graphitization step (the heat treatment step) may be performed byputting the stabilized fiber into a furnace, under an atmosphere ofinactive gas (nitrogen, argon), and then by performing a heat treatmentprocess. The graphitization process may be performed at a temperatureless than 2,500° C., at a temperature of at least 1,500° C.˜2,500° C.,or at a temperature of 1,500° C.˜2,000° C.

If the graphitization process is performed within the above temperaturerange, graphitization may be performed at a temperature lower than theconventional graphitization temperature for fabricating high-performancecarbon fiber. Here, graphite fiber (high-performance carbon fiber),which has the same performance or more excellent performance as/than theconventional one fabricated at a high temperature, can be provided.

With the graphene carbon fiber composition according to the presentdisclosure, high-performance carbon fiber can be fabricated at a lowergraphitization temperature than the conventional one for fabricatinghigh-performance carbon fiber.

Further scope of applicability of the present application will becomemore apparent from the detailed description given hereinafter. However,it should be understood that the detailed description and specificexamples, while indicating preferred embodiments of the disclosure, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the disclosure will becomeapparent to those skilled in the art from the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this specification, illustrate exemplary embodiments andtogether with the description serve to explain the principles of thedisclosure.

In the drawings:

FIG. 1 is a conceptual view illustrating a graphene carbon fibercomposition according to an embodiment of the present invention, andnano ribbon-shaped graphite obtained by heat-treatment (graphitization)the graphene carbon fiber composition;

FIG. 2 illustrates a high-resolution transmission electron microscopy(HRTEM) image (upper side on the right) of graphene powder fabricated inExample 1-1), an X-ray diffraction (XRD) pattern of graphene powder, andan XRD pattern of nano ribbon-shaped graphite after a graphitizationprocess, in which full with half maximum (FWHM) of the (002) peak whichnear 26° (2θ) are 7.9° and 2.6°, respectively;

FIG. 3 (A) (left) is an image illustrating a graphene suspension, aliquid-phase PAN-based graphene carbon fiber composition fabricatedaccording to Example 1 (weight of graphene based on the sum of PAN andgraphene powder: 10 wt %), and FIG. 3 (B) (right) is an imageillustrating the graphene suspension according to Example 1 in the formof powder through a drying process and a granulation process;

FIG. 4 (A) (left) is a transmission electron microscopy (TEM) imageillustrating nano ribbon-shaped graphite fabricated according to Example1, and FIG. 4 (B) (right) illustrates a TEM analysis result on nanoribbon-shaped graphite fabricated according to Example 3;

FIG. 5 (A) (left) is a transmission electron microscopy (TEM) imageillustrating nano ribbon-shaped graphite fabricated according to Example1, and FIG. 5 (B) (right) illustrates a TEM analysis result on nanoribbon-shaped graphite fabricated according to Example 3; and

FIG. 6 illustrates that a sample not including graphene powder has beenthermally-treated, in which full with half maximum (FWHM) of (002) peakshown near 26° (2θ) is 4.8°.

DETAILED DESCRIPTION OF THE DISCLOSURE

Description will now be given in detail of the exemplary embodiments,with reference to the accompanying drawings. For the sake of briefdescription with reference to the drawings, the same or equivalentcomponents will be provided with the same reference numbers, anddescription thereof will not be repeated.

Example 1

1-1) Fabrication of Graphene Nanopowder

Nano-sized graphene powder was fabricated by mechanical milling(decomposing) helical crystalline graphite structure (diameter: severaltens of nm, length: several μm).

An XRD analysis result on the graphene powder was shown in FIG. 2, andan HRTEM image of the graphene powder was shown on the upper rightcorner of FIG. 2.

Referring to FIG. 2, (002) peak of an XRD pattern appears to bebroadened, and an HRTEM image reveals disordered graphene layersalthough some of them are stacked in parallel. Graphene sheets have alength of 10 nm or less than and a thickness of 0.4 nm or less than Thedata prove that the sample was graphene in the form of a nanopowder.

1-2) Fabrication of Graphene Carbon Fiber Composition

0.2 g of the graphene powder fabricated according to Example 1-1) wasput in 10 cc of dimethylformamide (DMF), and the mixture underwent anultrasoncation, thereby fabricating a graphene suspension formed as thegraphene was dispersed into the DMF.

1.8 g of polyacrylonitrile (PAN, manufactured by Aldrich Co., Ltd.,weightaverage molecular weight: 150,000) and 100 cc of DMF were mixed toeach other, thereby fabricating a PAN solution (composition forfabricating carbon fiber). The graphene suspension and the PAN solutionwere mixed to each other, and the mixture underwent ultrasonication,thereby fabricating a graphene suspension, a liquid-phase PAN-basedgraphene carbon fiber composition (the amount of graphene powder was 10wt % based on the sum (PAN+graphene powder)). The graphene carbon fibercomposition of the present invention may be prepared in the form of thegraphene suspension, or a material formed as the graphene suspension hasa prescribed viscosity, or particles formed after the graphenesuspension is dried, etc.

FIG. 3 (A) (left) is an image illustrating a graphene suspension, aliquid-phase PAN-based graphene carbon fiber composition according toExample 1 (weight of graphene based on the sum of PAN and graphenepowder: 10 wt %). Referring to FIG. 3 (A), the graphene suspensionexhibited a uniform black color differently from a transparent PANsolution. From this, it was proved that the graphene powder wasuniformly dispersed in the PAN solution.

1-3) Heat Treatment of Graphene Carbon Fiber Composition

For heat treatment of a graphene carbon fiber composition, the graphenesuspension was dried in an oven to be granulated. As a result,fabricated was a powder-type graphene carbon fiber composition shown inFIG. 3 (B). In case of fabricating graphene carbon fiber, such processis not required, but a suspension viscosity controlling process and afiberization process are required. Prior to the heat treatment, thegraphene carbon fiber composition was stabilized at 300° C. for 3 hours.

The stabilized sample was put into a vacuum furnace, and then was heated(graphitization process) at a temperature of 2,000° C.

An XRD analysis result on the thermally-treated sample was shown in thelower graph of FIG. 2. Referring to FIG. 2, (002) peak was clearlyobserved near 26° (2θ). From this, it was proved that the graphenecarbon fiber composition was graphitized.

The graphitized sample was analyzed using high-resolution transmissionelectron microscopy (HRTEM), and an image thereof was shown in FIGS. 4(A) and 5 (A). Referring to FIGS. 4 (A) and 5 (A), nano ribbon-shapedgraphite having a thickness of several nm or less than, and a length ofseveral tens of nm is observed.

Comparative Example 1

A PAN carbon fiber composition fabricated in the same manner as inExample 1, except that graphene powder was not included, was stabilizedat 300° C. for 3 hours. Then, the PAN carbon fiber composition underwenta graphitization process at a temperature of 2,000° C. for 1 minute.

As shown in FIG. 6, full with half maximum (FWHM) of (002) peak was4.8°, which was much greater than 2.8° shown in FIG. 2 where thePAN-based carbon fiber composition includes graphene powder. This meansthat graphite is not well formed in a case where the PAN-based carbonfiber composition does not include graphene nano powder. From this, itcan be proved that the graphene powder of the present invention servesas a seed in a process of fabricating graphene carbon fiber.

Example 2

In Example 1, experiments were conducted on a change of formationbehavior of nano ribbon-shaped graphite, according to a change of theamount of graphene with respect to PAN, when fabricating the graphenecarbon fiber composition of Example 1-2) using the graphene nano powderof Example 1-1). The content of the graphene powder was lowered to 0.1wt % from 10 wt %, and the result was shown in the following Table 1.

When the content of graphene powder based on the sum of PAN and graphenein the graphene suspension is 0.5 wt % or more than, the sampleexhibited an entirely opaque black color. However, the sample wasgradually diluted when the content of graphene powder is 0.4 wt % orless than. Then, the sample exhibited a semi-transparent black colorwhen the content of graphene powder is 0.1 wt %.

Each graphene suspension was dried, and underwent the same process as inExample 1-3). The resulting materials were analyzed using XRD and TEM,and the degree of graphitization with respect to each sample was shownin Table 1. In a case where the nano ribbon-shaped graphite was wellformed (FWHM of (002) peak using XRD was 4.5° or less), it was expressedas ‘Excellent’. On the other hand, in a case where the nanoribbon-shaped graphite was not well formed (FWHM of (002) peak using XRDwas 4.5° or more), it was expressed as ‘Inferior’.

TABLE 1 Degree of Content of Formation of Nano Graphene Powder Contentof PAN Ribbon-Shaped (wt %) (wt %) Graphite Example 2-1 10 90 ExcellentExample 2-2 1.0 99.0 Excellent Example 2-3 0.5 99.5 Excellent Example2-4 0.1 99.9 Inferior

Referring to the above Table 1, in a case where each sample was dried toundergo a graphitization process at 2,000° C., graphitization wasperformed when the amount of graphene powder is more than 0.1 wt %.Also, graphitization was excellently performed when the amount ofgraphene powder is 0.5 wt % or more than. On the other hand, the seedeffect of the present invention was not observed when the amount ofgraphene powder is 0.1 wt % or less than.

From the above experiments, it could be proved that the content ofgraphene powder added to a graphene carbon fiber composition should bemore than 0.1 wt %, preferably 0.5 wt % or more than, for fabrication ofnano ribbon-shaped graphite when a graphitization temperature is 2,000°C. This means that the content of graphene powder added to a graphenecarbon fiber composition is preferably about 0.5 wt % or more than.However, the lower limit may be much lower than 0.1 wt %, according toan experimental method, an optimization of experimental conditions, etc.

Example 3

A pitch-based graphene carbon fiber composition was fabricated using thenano-sized graphene powder fabricated in Example 1-1), and usinganisotropy pitch (manufactured by Donga Carbon Fiber Co., Ltd.) ratherthan the PAN of Example 1-2). Suspension was mixed with the anisotropypitch. The content of the graphene powder was 10 wt % based on the sumof the anisotropy pitch and the graphene powder, in the same manner asin Example 1.

The pitch-based graphene carbon fiber composition underwent astabilization process and a graphitization process, in the same manneras in Example 1.

The experimental results obtained in Example 3 were similar to those inExample 1. As shown in the TEM images of FIGS. 4 (B) and 5 (B), observedwas nano ribbon-shaped graphite having a thickness of several nm or lessthan, and a length of several tens of nm. Further, as an XRD analysisresult at (002) peak (FWHM: 3° or less than) was clearly observed near26° C. (2θ) in the same manner as in Example 1. This means thathigh-performance carbon fiber can be fabricated at 2,000° C. ifnano-sized graphene is added to a graphene carbon fiber composition, incase of pitch-based carbon fiber.

Referring to the results obtained in Examples and Comparative Example,in the examples where graphene powder was added to a graphene carbonfiber composition, a graphitization process was excellently performedeven at a temperature of 2,000° C. This means that high-performancecarbon fiber can be fabricated at a temperature of 2,000° C. lower thanthe conventional 2,500° C. or more than by about 500° C.

The foregoing embodiments and advantages are merely exemplary and arenot to be considered as limiting the present disclosure. The presentteachings can be readily applied to other types of apparatuses. Thisdescription is intended to be illustrative, and not to limit the scopeof the claims. Many alternatives, modifications, and variations will beapparent to those skilled in the art. The features, structures, methods,and other characteristics of the exemplary embodiments described hereinmay be combined in various ways to obtain additional and/or alternativeexemplary embodiments.

As the present features may be embodied in several forms withoutdeparting from the characteristics thereof, it should also be understoodthat the above-described embodiments are not limited by any of thedetails of the foregoing description, unless otherwise specified, butrather should be considered broadly within its scope as defined in theappended claims, and therefore all changes and modifications that fallwithin the metes and bounds of the claims, or equivalents of such metesand bounds are therefore intended to be embraced by the appended claims.

What is claimed is:
 1. A graphene carbon fiber composition, comprising:a composition for fabricating carbon fiber; and graphene powder, whereinthe composition for fabricating carbon fiber includes one selected fromthe group consisting of polyacrylonitrile (PAN)-based carbon fiber,pitch-based carbon fiber, rayon-based carbon fiber and combinationsthereof, and the graphene powder serves as a seed of graphite to beformed during carbon fiber fabricating processes.
 2. The graphene carbonfiber composition of claim 1, wherein the graphene powder is fabricatedby decomposing crystalline graphite, and has a length of 20 nm or less.3. The graphene carbon fiber composition of claim 2, wherein thecrystalline graphite is a graphite structure grown in a helix shape. 4.The graphene carbon fiber composition of claim 1, wherein a content ofthe graphene powder is more than 0.1 wt % based on 100 wt % of the sumof the composition for fabricating carbon fiber and the graphene powder.5. The graphene carbon fiber composition of claim 1, further comprisinga solvent, wherein the solvent is selected from the group consisting ofalcohol, acetone, dimethylformamide (DMF), tetrahydrofuran (THF) andcombinations thereof.
 6. A method for fabricating high-performancecarbon fiber, the method comprising steps of: a mixing step to fabricatea graphene suspension by mixing a composition for fabricating carbonfiber with graphene powder to form a graphene carbon fiber composition,and dispersing the graphene carbon fiber composition in a solvent,wherein the composition for fabricating carbon fiber includes oneselected from the group consisting of polyacrylonitrile (PAN)-basedcarbon fiber, pitch-based carbon fiber, rayon-based carbon fiber andcombinations thereof; a fiberization step to fabricate fibers bycontrolling a viscosity of the graphene suspension; a stabilization stepto stabilize the fibers by heating at 200-400° C. under atmosphere; anda heat treatment step of fabricating nano ribbon-shaped graphite bygraphitizing the stabilized fibers at a temperature less than 2,500° C.,wherein the graphene powder included in the graphene carbon fibercomposition serves as a seed of graphite to be formed duringhigh-performance carbon fiber fabricating processes.
 7. The method ofclaim 6, wherein the graphitization of the heat treatment step isperformed at a temperature range of 1,500° C. and greater to less than2,500° C.